Sitemaps, Meta Data, and robots.txt Forum

My robots.txt validates, but has "bad style". I thought it is common practice to allow and use comments either on lines by themselves, or after code on a line, in all computer languages. Just looking for reasoning that makes this "bad" style. I could easily move it up to the line preceding, but I'm just curious why it matters. What problems does it cause to do it this way?

warningComments were detected after a valid field name. Although ok, this is bad style.